During the past four years the DERC with its core laboratories and support for pilot and feasibility studies has greatly contributed to expansion in scope and intensity of the research at the Joslin. Over this period there has been more than doubling of research at the Joslin. Over this period there has been more than doubling of research fellows and a 50% increase of faculty in the Research Division. Recognizing the importance of this expansion and the resulting space shortage it has created, the Trustees have committed to expansion of the Joslin Diabetes Center by adding three floors to the current building (adding over 40,000 square feet of additional research space). In its financial import and support of interdisciplinary studies utilizing multiple tools of biomedical research and its support of junior faculty, the DERG is an essential component of this planned expansion as well as for the maintenance of current efforts. In this renewal, we have proposed a reduction in some current activities to accommodate two new cores (Transgenic Mouse Facility, Electron Microscopy), and a new subcore (Genetics). We have expanded the mission of the radio- iodination facility to that of a Peptide Biochemistry Core with the availability of a peptide synthesizer. We have also planned the addition of one pilot and feasibility grant to our Center for use by scientists outside the joslin in the Longwood area and affiliated Harvard hospitals.